Biol 3301 ch 6

Hardy Weinberg theory

population mating at random in absence of evolutionary forces, allele frequencies will remain constant.

Hardy Weinberg theory examples

natural state for our population is to remain the same with same forces

Hardy Weinberg equilibrium conditions

random mating, no mutations, large population size, no immigration, equitable fitness between all genotypes

no immigration violated

gene flow

large population size violated

genetic drift (moving around the genetic pool with no direction)

equitable fitness violated

natural selection

biggest impact on population

natural selection, sexual selection

mutation

random change in the sequence of nucleotides

random mechanisms

just happen, very little direction

recombination

reshuffling of genes, DNA copied during meiosis, chromosomes exchange genetic material

random assortment

making haploid gametes, combination of alleles in given gamete

nonrandom mechanisms

individuals select mates based on specific traits, or where selection pressures favor certain traits over others, leading to changes in the genetic makeup of a population

biggest random change

genetic drift

genetic drift

random processes can change gene, mating mortality, fecundity, inheritance

change due to chance

small population, genetic drift

habitat fragmentation

reduces habitat availability and connectedness, separates population

separates populations does what

decreases local population size which isolates gene pools

bottleneck effect

reductions of genetic diversity in a population due to a large reduction in population size

genetic variation lower at

isolated island and smaller island populations

founder effect

small number of individuals leave a large population to colonize a new area bringing small amount of genetic variation

gene flow

movement of individuals between different species

open populations

individuals move between sub populations

high rate of interchange

common gene pool, less likely cause change, sub population gene pools are similar

low rate of interchange

genetic diversity, immigrants enter with different allelic frequencies, leads to evolution

non random gene flow

certain genotypes are more or less likely to move between populations than others

stabilizing selection

against extreme phenotypes and facing average phenotypes

Hardy Weinberg requires

equal participation in mating, lack of consistent choice in mating

sexual selection

mates chosen non randomly, certain individuals have greater chance of obtaining mates

sexual selection based on

perceive quality, proximity(inbreeding)

inbreeding

individuals mate with others who are closely related to them than expected by random chance

What does inbreading cause

homozygosity at all genes, inbreeding depression

inbreeding depression

offspring are most likely to be homozygous for harmful recessive alleles, lead to reductions in fertility, vigor, fitness, and even death

homozygosity

genes that have the same alleles

differential survival and reproduction

some individuals produce more offspring due to phenotypic characteristics and environment

microevolution

evolution of populations, artificial selection of dogs, industrial melanisms of moths, selection by predators

macroevolution

evolution at species or higher level

allopatric speciation

evolution of new species through the process of geographic isolation (two different spaces)

sympatric speciation

evolution of new species without geographic isolation, arise from habitat variation